Human pluripotent stem cells (hPSCs) are promising cell source to produce therapeutic endocrine cells for diabetes treatment. A gel solution made by decellularized tissue-specific extracellular matrix (dpECM) significantly promotes three-dimensional (3D) islet-like organogenesis during induced hPSC differentiation into endocrine lineages. Islet organoids are self-organized even in a two-dimensional (2D) culture mode. Cells derived from hPSCs differentiated on such ECM coated substrates exhibit similar cellular composition to native pancreatic islets. These cells express islet signature markers insulin, PDX-1, C-peptide, MafA, glucagon, somatostatin, and pancreatic polypeptide, and secrete more insulin in response to glucose level compared to a traditional matrix substrate (Matrigel). The dpECM facilitates generating more C-peptide+/glucagon− cells rather than C-peptide+/glucagon+ cells. Remarkably, dpECM also facilitated intra-organoid vascularity by generating endothelial cells and pericytes. Furthermore, dpECM niches also induced intra-organoid microvascularization during pancreatic differentiation.